1. Field of the Invention
The present invention relates broadly to a novel transfer media or ink composition, which when coated on a thin flexible substratum is useful in the production of typewriter ribbons, carbon paper and the like, and more particularly to an adhesively correctable film typewriter ribbon having a delayed alteration resistance which is especially adapted for use in conjunction with an adhesive lift off tape of the type that is used to lift off typed indicia. The delayed alteration resistance typewriter ribbon made in accordance with the present invention is especially adapted for use with lift off tapes and typewriters such as the Correcting Selectric typewriter manufactured by Internation Business Machines Corporation. This invention eliminates complete adhesive "lift off" of typewritten indicia from the typing bond after a predetermined time duration while allowing for complete adhesive removal of any image a short time after the indicia is typed or transferred onto typing bond.
2. Description of the Prior Art
Transfer media now in common use and known as "correctable film ribbons" usually comprise a flexible carrier substrate such as polyethylene, or the like on which is coated a pressure sensitive transfer coating. Upon type font impact or stylus pressure such ribbons produce impressions on typing bond paper or similar surfaces. The correction of erroneously typed impressions is accomplished by the utilization of a lift off tape or tabs.
The lift off tapes or tabs consist of a flexible carrier substrate, such as polyethylene terephthalate that is provided on one side with an adhesive coating, which, when brought into firm contact with typed impressions, will adhesively remove or "lift off" such impressions. Corrections made in this manner have the advantage of being virtually invisible. This, however, is also their disadvantage, particularly in the case of legal documents and commercial paper. The ability to correct an error undetectably at some later time can also be used to falsify documents which cannot readily be detected.